The present invention relates to a bellows pipe made of synthetic resin, which is suitably used mainly for a drain pipe of a domestic washing machine and an air blowing pipe of a drier for drying futon mats.
Conventionally, a large number of bellows pipes of this type have been proposed and well known, in which the section of the pipe wall is formed to be substantially triangular, and one inclined wall can be made to be approximately parallel with the other inclined wall so that the bellows pipe can take a shortened posture, and this shortened posture can be maintained by itself. For example, there is provided a bellows pipe, the thickness of which is small, that is, the thickness is about 1 mm or less, and the diameter of which is 30 to 40 mm. This bellows pipe is already applied to an air blowing pipe of a futon mat drier for domestic use. The present applicant has made an application for patent of this type bellows pipe used for a drain pipe of a domestic washing machine. The example is shown in Japanese Unexamined Utility Model Publication No. Hei. 5-1486.
Although a large number of bellows pipes of this type have been proposed, the wall thickness is small as described above, and the pipe wall is in a single structure. Therefore, during usage of the bellows pipe over a long period of time, a top portion of the pipe wall wears away or when the bellows pipe is hooked by some other objects, it is damaged. Thus, in the case of a drain pipe of a washing machine, an unforeseen leak of water occurs, and in the case of a futon mat drier, the capacity is accidentally lowered.